#define _CRT_SECURE_NO_WARNINGS 1
typedef struct ListNode LN;
int kthToLast(struct ListNode* head, int k) {
    LN* fast = head, * slow = head;
    while (k--) {
        fast = fast->next;
    }
    while (fast) {
        slow = slow->next;
        fast = fast->next;
    }
    return slow->val;
}
